Segmental grinding wheel



Feb.2, 1932. T. LARSSON Y 1,843,287

S EGMENTAL GRINDING WHEEL Filed Dec. 15, 195o 2 sheets-sheet 1 WITNESS 72H/EE LHRSsoN ANR H. gm-CZ CQHTN Feb- 2, 1932. T, LARSSO 1,843,287

l SEGMENTAL GRINDING WHEEL Filed Deo l5, 1930 2 Sheets-Sheet 2 Jmmkoc THufE L qfssoN WITNESS www QQAFLQTWM Patented Feb. 1932 'l UNITED STATES PATENT olii-ica4 THURE LARSSON, I' WORC'ESTEE, IABSAQCHUSETTS, ASSIGNOB '.lO NORTON COMPANY, 0F 'WORCESTER MASSACHUSETTS, A' CORPORATION 0F MASSACHUSETTS sEGxaNTAL 'emma' WHEEL -being handled and transported independently of any rotatable support upon which it v may later be mounted torotate. therewith and perform a grinding operation. p

It has been found highly impractical to manufacture large monolithic abrasive wheels composed of abrasive grains bonded together by a vitriied ceramic material suf ficiently strong to withstand the high rate of rotation necessary for many of the present day grinding operations Furthermore, the firing operation for these large wheels may often result in their breakage, since it is practically impossible to heat a large abrasive l mass with uniformity and thereby maintain an even. expansion throughout the entire wheel structure. As a consequence, it has been found advantageous to construct many of the large size abrasive vwheels from a multiplicity of abrasive segments which are individually clamped inA position upon the peripheral surface of a large cast irondrum and thereafter cemented in place, thus forming an integral wheel structure capable of a high speed rotation without any of the-inherent structural weaknesses of the previous monolithic wheel constructions. Owing 'to their great size and massive weight, these cast ironn supporting drums have been expensive to manufacture and ship. In assembling Wheels of this type, there is a loss of time which involves further expense since each individual segment must be accurately fitted and firmly clamped in its respective p'osition upon the peripheral surface of the supporting drum. Furthermore, av massive cast iron supporting drum of this type may adda weight of several tons to the abrasive an'nulus which necessitates a large supporting shaft and immense bearings therefor.

Whenever one of these massive wheels breaks down or wears out, it is necessary to return the entire wheel and supporting drum to the factory for repair or replacement of new segments upon the old drunr. Obviousapplication ma December 15, mso. 'semi no. 502,314.

ly, such a repair places the grinding machine in an inoperative condition for a considerable time as well as involving the expense of dismantling the machine, forcing the heavy drum from its shaft, shipping it and the abrasive annulus aiiixed thereon/to the 'fac tory for repairl and then back to the grinding machine for reinstallation upon its shaft. Mounting a massive grindingwheel of this type usually requires skilledlabor and speola-l equipment since such a grinding wheel may often weigh several tons vand rt uirecareful balancing upon its supporting s aft. The wheel users onlyalternative to save this expensive delay has been to keep a spare `grlnding wheel on hand, which often involved an expense of several thousand dollars.

Therefore, thev principal object of my invention is to providea segmental grinding wheel having a multiplicity of abrasive segments intimately secured together and forming' a substantially unitary abrasive annulus which may be transported independently of and removably mounted uponany rotatable support of a'standard A further object is to provide a segmental grinding wheel in which the abrasive segments are interlocked with a seriespof supporting members and form an integral wheel structure rigidly mounted upon a rimless rotatable -support and thereby avoidv the ex'-r pense and time involved in fitting the segments rto the peripheral surface of a' sup'- port-ing drum.

In accordance with my invention, I have provided a unitary segmental abrasive wheel composed of a plurality of separately manuinterlock to hold the segments together but lsis also a rimless support which carries the radial pressure on the wheel segments.

lf desired, the abrasive annulus may be constructed tobe integral with the central rotatable support, in which case the interlocking girders are rigidly and permanently secured to rotatable supporting members, and as in the former case they provide a rimless support as distinguished from the supporting drum used heretofore in this art. The abrasive segments are laterally slid into position between adjacent girders and interlocked therewith by means of any suitable cementitious filler inserted into the crevices between the adjacent parts, thus forming an integral and rigid wheel structure. In this construction, when the wheel is worn out the entire structure must be discarded or shipped back to the factory for removal of the old abrasive segments and replacement of new ones in their stead.

I have illustrated in the accompanying drawings embodiments of both types of my invention, wherein Figs. 1 to 6 show segmental grinding wheel structures having an abrasive annulus which may be transported independently of any rotatable support and Figs.

to 10 show a segmental grinding wheel structure wherein the abrasive body and its rotatable support comprise a unitary structure.

Referring to Figs. 1 to 6, Fig. 1 is a perspective view of an assembled grinding annulus having a portion thereof broken away to more clearly illustrate the method of interlocking the adjacent abrasive segments and girders;

Fig. 2 is a fragmentary Vview showing a girder member embedded within the cement and locking two adjacent segments together;

Fig. 3 is a sectional view showing a method for removably mounting a unitary abrasive annulus upon a supporting hub for rotation therewith:

Fig. 4 is a fragmentary-view whichshows a modified form of an abrasive annulus adapted to be removably secured to a supporting hub;

Fig. 5 is a sectional view taken substanmuy along the une 5 5015 Fig. 4; and

Fig. 6 is a. sectional view taken along the line 6 6 of Fig. 4.

Referring to Figs. 7 to 10, Fig. 7 is a per-` to more clearly illustrate the unitary wheel structure;

Fig. 8 is a perspective view of the girdcr which fastens the side plates together and interlocks with adjacent wheel segments to form a unitary wheel structure;

' Fig. 9 is a fragmentary View taken in elevation showing the wedge shaped abrasive segments and their relative positions in the finished wheel structure; and

Fig. 10 is a fragmentary View in central section along the irregular line 10-10 of Fig. 9.

As illustrated in Figs. 1, 2 and 3 of the drawings, the preferred forni of my invention comprises a substantially unitary abrasive annulus l0 which is transportable independently of a rotatable support upon which it may be removably mounted. This abrasive'annulus 10 consists of a plurality of similar, individually fashioned, wedgeshaped, arcuate segments 11 composed of abrasive grains bonded together by any suitable vitrified ceramic materials, and' these segments are positioned with adjacent radial faces 13 spaced apart so that their external curved surfaces together form a cylindrical grinding face. The end faces 14 of the segments 11 are cuneated or dovetailed in form, and each radial face 13 of the segment is provided with reentrant surfaces 15 forming a groove which cooperates with the opposed groove on the adjacent segment to carry a girder member 18. These girdcr members 18 are preferably arranged substantially parallel to the axis of the abrasive annulus and are positioned radially of the grinding annulus so that a girder may fit between each two adjacent segments and interlock` therewith.

The girder members 18 are single piece at Y metal bodies comprising a flange or base 20 from which rises a radial web 21 terminating in an enlarged head 22 which is shaped to lit within both of the reentrant portions of the two adjacent segment-s and interlock therewith when the abrasive annulus is assembled. The top of the base 20 serves to form two supporting shoulders 23 one upon each side of the web 21 which locate and radially support the abrasive segments in correct position for rotation. The head 22 and the shoulder 23 interlock with the dovetailed portion of the segment andsupport it against radial stresses due to centrifugal and centripetal forces arising during transportation or use during a grinding operation.

To securely bind the abrasive segments and girders together into an integral annulus which is readily transportable as a unit independently of any rotatable support, I have secured the various members of this structure together by any suitable cementitious medium 24, examples of which are a molten metal, such as lead or babbitt, and a rac - Thus all of the strains due to centrifugal Leraar? 'When thus made, the abrasive annulus may be rigidly mounted on a rimless supporting center, and removed therefrom as desired.

To removably fasten my grinding annulus 10 to a rotatable support or hub for rotation therewith, l provide lneans for` securing the gir-ders to a central rotatable support,'which may be so arranged that the annulus may be either removable therefrom or permanently secured theretou ln the form shown in Figs. l to 6, the annulus is made removable, and one suitable means for so doing may comprise holes 25 within the end faces of each girder base 20 whichin the present instance are tapped to receive threaded studs 27 passing through and secured 'by nuts 28 to two disk-like lates 29 removably mounted upon a hub 30 by means of a series of cap screws 31 threaded into anges 32 upon either end of said hub. To prevent any undue strain or excess shearing action upon the studs 27 and cap screws 3l, l have provided the cen trai bore of each plate 29 of such size that it may lit snugly over the hub 30 and ll have also provided a recess and flanged portion 33 adjacent to the periphery of each plate 29, so shaped that it will mate with a similar re cess and iiange portion 3d upon the end faceI of the base 20 of each girder member 18.

and centripetal forces aretransmitted from the abrasive annulus 10 through the girder members 18 which are rigidly secured to the plates 29 and thence directly to the hub 30 without creating any dangerous shearin action upon the studs and cap screws whic i hold the various parts in proper, location relative to one4 another.

To assemble my abrasive annulus and 4form an integral grin in structure which may be removably mountev upon any standard size supporting plates and hub, l provide a pair of master plates which are identical with the standard size plates 29 upon which the girder members are inally removably mounted,

rlhe girders 18 are rigidly fastenedin correct location by means ci studs 27 and nuts 28, thus supporting the girders in exact position pre.,n paratory to assembling the abrasive-segments therewith. The abrasivesegments are individually and-laterally slid into position between each pair of -girder members so that the dovetailedfportion of each segment may interlock between the opposed heads of adjacent girders. During assembly the segments are circumferentially spaced so that they doV not engage one another or the' girders, and the interstices between the adjaent radial faces 13 and between the girders and abrasive faces adjacent thereto are filled by casting the lcementitious medium 24 therebetween. In this way the segments and girders are permanently secured in their correct relative positions and thereby form an integral abra- `sive annulus having a series of girder membersl embedded therein. When the cementitious medium has set, the vnuts 28 may be removed and the abrasive annulus and girders removed from the master plates as an integral structure and shipped as a unit to its destination where it may be quickly and easily asleibled upon any standard size plates and l have shown in Figs. 4, 5 and 6 a modified form of my segmental abrasive annulus which may be transportable as an independent unit and removably secured upon any standard size of rotatable support thereforto perform a grinding operation. My annulus is coniposed ofa plurality of radially spaced abrasive segmentsO havingr opposed radial aoes 41 and cuneated or dovetailed portions therebetween which are interlocked'with spaced girders 42 radially positioned between each pair of adjacent segments and further secured in correct position by a suitable cementitious iller 44 of the type heretofore described which is cast in position so that it completely fills the interstices between the faces land between the segments and girders. piece'metal body having a web d3 terminating in an enlarged rounded head l5 which has a hole Grunning longitudinally therethrough and within which a stud 47 may be slidably ety Each girder 42 may comprise a single idd mounted to secure the girder and segments v interlocked therewith to a rotatable support.

rllhe end faces of the girders are so formed that each girder is dovetail shaped in longtudinal cross section and is rigidlybut removably fastened between two supporting disks 48 by means of nuts 49 screwed upon both ends of studs a7 as clearly illustrated in Fig. 5. The disks d8 are further provided with recessed and flanged surfaces adjacent I their peripheries which mate positively with and .engage the dovetailed form of each gird.

er, thus preventing any shearing action upon the clamping studs 47 due to radial forces exerted upon the wheel during rotation. Each abrasive segment Ois, further provided with a dovetail portion in cross section of similar shape to that of the girder members but of slightly smaller size so that the disks may firmly clamp against each girder member but lwill `prevent the individual Vsegments from i 'flying from the wheel during its use in case of breakage. as shown in Fig. 6. The side faces of the dovetailed portions upon the segments and girders are cut below t-he side faces of the segments so that none of the supporting parts will extend beyond thepside faces of the wheel should it be desired to use it for a plunge cut grinding operation.

To assemble 'my abrasive annulus of the modified construction as shown in` Figs. 4, 5 'and 6 and form an integral grlnding structure which may be removably secured upon any standard size supporting plates and hub, I have provided two master disks which are identical with 'the standard size disks 48 upon which the girder members 42 and segments 40 are finally removably mounted. The segments 40 and girders 42 are mounted in spaced relation and clamped in position by studs 47 and nuts 49. During assembly, the segments are circumferentially spaced sothat they do not engage each other or the girders, and the spaces between the girders and the adjacent segment faces and between the adjacent radial faces are filled by ycasting the cementitious medium 44 therebetween. Thus .each segment and girder is positively secured in correct relative position, and when assembled, they form an abrasive annulus having a series of girder members embedded therein. When the cementitious filler has set, the nuts 49 may be removed, studs 47 withdrawn and the abrasive segments and girders removed from the master plates as an integral structure which may be transported as an independent unit to its point of'use when it may be quicklyI described, which are positioned with their radial side faces 51 spaced apart so that the outer curved surfaces of the segments together form a cylindrical face. The end portions 52 of each segment are dovetailed in formand having inner radial faces 51 and reentrant sprfaces 53 so arranged that during assembly the individual segments may be laterally slid into position in a direction arallel to thev axis of rotation bet-Ween the girders 55.

In order to avoid use of a heavy and expensive cast iron drum or other wheel structure which provides a cylindrical rim or peripheral surface upon which the abrasive segments may be secured, I similarly construct Athe wheel mount of two plates or disks 56 diallyof the wheel. The girders 55, as illustrated in Fig. 8, may be made of a single piece of metal provided with two depending ianges l59 at either end and at right angles to the web 58 and parallel with the supporting plates 56 to which they are permanently fastened by rivets 62. These depending ianges 59 are connected and strengthened by a central web 63 which ,is a continuation of web 58. `Each girder is further provided with two flanges forming shoulders 64 adjoining the opposite sides of webs 58 which are parallel to the heads 57 and serve to su port the abrasive segments thereon. T e lwebs 58 projectbeyond and overhang the)y flanges 59 (see Figs. 8 and 10) so that the disks 56 may be properly positioned with their peripheries in engagement with the under surfaces of these Webs to better streng'ltwllen the abrasive wheel during grinding. us lthe disks are maintained in rigid spaced relationship by the same members which serve to support the abrasive segments and lock themin position.

The disks 56 may be mounted in spaced .relationship directly upon a driving spindle, but I prefer to support them u on a hub 66. To this accomplishment, the dis s 56 are provided with central holes of such size that` they fit snugly over the end of the hub 66.

The hub portion extending between the disks 56 is provided with radiating arms 67 to which .the disks are p-ermanentl secured by rivets 69 passing through both isks and the res ective arms upon said hub.

n assembling this wheel the hub 66, the plates 56 and the girders 55 are first fastened together' permanently, after which the segments are slid laterally into position between their` respectivegirders with which they interlock. The interstices between adjacent radial faces 61 of the segments and between the girders and the segment faces adjacent thereto are filled with a suitable cementitious medium 69, such as described above. As soon as the cementitious medium has hardened and set, the abrasive wheel is ready for shipment and use. i

This case is a continuation in part of my prior application, Serial No. 257,244 filed February 27, 1928 and allowed September 19, 1930.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding wheel comprising a multiplicity of abrasive segments, a series of girder members each of which is interlocked with two adjacent segments, a cementitious medium cast between the adjacent segments y Lames? and enveloping that portion of each girder member which lies therebetween and means whereby said girder members may be remov-` ably mounted at their opposite ends ona rotatable support.

2. A segmental grinding wheel comprising a multiplicity of abrasive segments arranged independently of any rotatable support to :form an annulus, each pair of adjacent segments .havin opposed reentrant rooves therebetween orming locking shoulers, a plurality of girders located between adjacent segments and interlocking with the opposed shoulders, a cementitious filler in said grooves which envelops the girders and secures cach segment rigidly in position, and thereby forms a unitary wheel structure and means whereby the girders may be removably fastened to a support and thewheel be mounted thereon. 4

3. A grinding wheel comprising an annulus of abrasive segments, each'having an inner dovetailed portion, a series of `clamp- `ing girders having opposed heads and supportmg portions located betweenv adjacent segments and so positioned'that cach dovetailed portion is supported by and hrmly se- Acured between two adjacentgirders, and a byforming aunitary abrasive annulus with cementitious filler between the laces of 'adje-- cent abrasive segmentsk and the girders, therethe girders embedded therein which is independent of any rotatable support.

;. 4L A grinding wheel comprising an annulus of abrasive segments, each havin an inner dovetailed portion, a series ol c amping girders having opposed heads and supporting portions located between adjacent segments and so positioned that each dovetailed portion is supported by and rmly secured between two adjacent girders, acementitious ller between the faces of adjacent abrasive segments and the girders, thereby forming a unitary abrasive annulus with the girders embedded therein and means whereby said girders may be removabl and rmly mounted upon a central Vhub or rotation of said annulus therewith.

5. A grinding wheel comprising a hub, two plates removably secured thereto, a plurality of peripherally spaced rders removably afred to said plates, eaco said girders having peripherally extending dangers at its base and a radially extendin web portion terminating in an enlarged' cad, a multiplicity of spaced abrasive seents, each of which is mounted between and supported by the flanges on two adjacent girders and has a cuneated ortion interloczn: with two' opposed gir er heads, a cementitious Edler between theadjacent abrasive scents and the irders forming an integral ding annuus, and means for removably securing the girders upon the plates.

.of rotation in assemblin 6. A 'nding wheel comprisin a rimless supporting center a plurality of girders having undercut heads rigidl mounted on said center and arranged para lel with the wheel axis, spaced abrasive segments assembled to form a peripheral grindin surface which have dovetailed portions idable between saidheads and are supported solely on said girders, and a cementitious filler between the segments and said heads and between adjacent faces of the segments whichvsecures the latter rigidlyV in position`and forms an inteoral wheel structure.

d. A grinding wheel comprising two disks spaced at their peripheries and arranged to be mounted centrally on a spindle, a plurality of spaced girders rigidly connecting the disks at their peripheries, each girder having a head arranged parallel .with the wheel axis, spaced abrasive segments arranged to form aperipheral grinding surface v,which have dovetailed portions slidable between said heads and are supported solely on said girders, and a cementitious iiller between the segments and said heads and between adjacent faces of the segments whicp secures the latter rigidly in position and orme an integral wheel structure; t f

8. A grinding wheel comprising a hub, a plurality of plates securedthereto, a plurality of girders @cured to the internal faces of the plates adjacent their peripheries and arranged to form a sectional rim having a plurality of spaced upst riding webs provided Y with heads, abrasive segments mounted on the rim in spaced relation to form a grinding surface, the segments having reentrant shoulders which interlock with the heads on the webs, and,y a hller in the interstices which remain between the adjacentv faces of the segments and the heads after the parts have been assembled. y

webs having cooperatin 'interlocking sur-.

faces necessitatin the sli ing of the segments on the webs in a irection parallel to the axis the segments between the webs, and a li er dowed' 'into the interstices remaining between the adjacent faces of theseginents and heads after the assembly oi? the parts..

l0. A. indio wheel comprising a hub, a pair of spaced- 'sks mcured'thereto, a rim composed ot a plurality of separate units secured near the peripheries bf thedisks, each of said units having integral therewith an upstanding web provided with a wedgeico lief

shaped head, abrasive segments mounted on the rim in spaced relation, each segment having a cuneated portion to fit in between a pair of the heads, and a filler in the interstices between the adjacent faces of the segments and the heads which makes an integral wheel structure thereof. l

l1. In a wheel structure for supporting a plurality of abrasive segments rigidly held together to form a cylindrical grinding surface, a hub, a plurality of arms radiating therefrom, a pair of disks positioned on the hub on opposite sides of the arms and secured thereto, and a plurality of irders mounted between the disks adjacent t eir peripheries,

' each girder having ay pair of plates one of which is secured to one of the disks and the other one of which is secured to the other disk, a web between the plates to hold the peripheries of the disks from relative movement, a to plate centrally positioned on the web Yand orming one element of the wheel rim and an integral web projecting outwardly irom the top plate constructed to have interlocking engagement with a pair of adjacent segments.

12. A grinding wheel mount comprising` a pair of parallel disks mounted on a hub or rotation, a series of girders rigidly connecting the peripheral portions of the disks, and spaced wedge-shaped heads arranged on the 'rders to hold abrasive segments thereetween.

13. A grinding wheel comprisinga pair oi parallel disks mounted on a hub, a series of peripherally spaced transverse girders rigidliy connecting the peripheral ortions of the isks and providing s aced en arged heads, a series of separately ashioned a rasive segments having inwardly projecting portions, each head being located between and interlocked with two adjacent segments, and means to secure the segments rigidly in position.

14. A grinding wheel comprising'a pair of parallel disks, a series of peripherally spaced girder like heads rigidly fastened to and between said disks adjacent to their peripheries, independently fashioned abrasive segments, each of which has a reduced portion supported by and interlocked between two adj acent heads, and a cementitious ller between' the adjacent segments forming an integral grinding wheel structure.

Signed at Worcester, Mass., this 13th day of Dec. 1930.

THURE LARSSON. 

